WiFi Range Extender - 1200Mbps WiFi Repeater Wireless Signal Booster, 2.4 & 5GHz. Wireless Signal Booster WiFi AC 1200 Dual Band Repeater Router AP Range Extender. Estimated between Wed. 24. Estimated delivery dates- opens in a new window or tab include seller's handling time, origin ZIP. Look at Wi-Fi signal level & link speed in AR-mode. Application uses Google ARCore, it will be additionally requested to download. List of supported devices. $0.99 - $24.99 per item. Flag as inappropriate. Wi-Fi Solutions. Google WiFi has intelligence that determines when the 2.4 GHz bands will provide a more stable connection versus 5.0 GHz. So suffice it to say, you will be connected to 5.0 GHz most of the time, that’s assuming your phone or tablet support that band.
This document covers the basics of how wireless technology works, and how it is used to create networks. Wireless technology is used in many types of communication. We use it for networking because it is cheaper and more flexible than running cables. While wireless networks can be just as fast and powerful as wired networks, they do have some drawbacks.
Reading and working through Learn Networking Basics before this document will help you with some of the concepts used in wireless networks.
In addition to some background information, this document covers six basic concepts:
Reading through this material should take about an hour. Working through the activities, or diving deeper into the subject with a group may take longer.
Wireless signals are important because they can transfer information -- audio, video, our voices, data -- without the use of wires, and that makes them very useful.
Wireless signals are electromagnetic waves travelling through the air. These are formed when electric energy travels through a piece of metal -- for example a wire or antenna -- and waves are formed around that piece of metal. These waves can travel some distance depending on the strength of that energy.
For more on how electromagnetic signals work, check the #External Resources section at the end of this document.
There are many, many types of wireless technologies. You may be familiar with AM and FM radio, Television, Cellular phones, Wi-Fi, Satellite signals such as GPS and television, two-way radio, and Bluetooth. These are some of the most common signals, but what makes them different?
First of all, wireless signals occupy a spectrum, or wide range, of frequencies: the rate at which a signal vibrates. If the signal vibrates very slowly, it has a low frequency. If the signal vibrates very quickly, it has a high frequency. Frequency is measured in Hertz, which is the count of how quickly a signal changes every second. As an example, FM radio signals vibrate around 100 million times every second! Since communications signals are often very high in frequency, we abbreviate the measurements for the frequencies - millions of vibrations a second is Megahertz (MHz), and billions of vibrations a second is Gigahertz (GHz). One thousand Megahertz is one Gigahertz.
| Example Frequency Ranges Below we can see the span of frequencies that are commonly used in communications. Broadcast transmitters for AM, FM and Television use frequencies below 1000 MHz, Wi-Fi uses two bands at higher frequencies - 2.4 and 5GHz. Cellular phones use many different frequencies.
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In addition to having different frequencies, wireless signals can be different in the way they convey information. A wireless signal needs to be modulated--or changed--to send information. There are many types of modulation, and different technologies can use one or more types to send and receive information. In the two examples below -- AM and FM radio -- the M stands for modulation. The type of modulation is what makes them different.
Example one: AM radio. The A in AM comes from Amplitude - the energy or strength of the signal, operating at a single frequency. An un-modulated AM wave might look like:
And a modulated AM radio wave has higher and lower energy (amplitude) waves indicating higher and lower audio frequencies in the signal:
From left to right, we have the normal, un-modulated wave, then the lower amplitude wave (representing low points in audio waves), then the higher amplitude wave (representing crests or high points in audio waves).
A more detailed version of an AM signal is below:
The audio signal is the wave on the top, with the corresponding Amplitude Modulated wave below it.
Example two: FM radio. The F in FM comes from Frequency - defined by how quickly the wave vibrates every second. An un-modulated FM wave might look like:
And a modulated FM radio wave has higher and lower frequencies indicating higher and lower audio frequencies in the signal:
From left to right, we have the normal, un-modulated wave, then the lower frequency wave (representing lower audio amplitudes), then the higher frequency wave (representing higher audio amplitudes).
The type of modulation various technologies use to communicate can be very different, and are often not compatible. Satellite equipment cannot speak directly to your laptop or smartphone, which uses Wi-Fi to send and receive information. This is because the radios in different devices can listen only to certain types of modulations and frequencies.
As an example, some broadcast radio receivers have a switch to select between AM and FM signals, for two reasons: they use different frequencies to transmit, and they use different modulation types. If you try and listen to an AM signal with a radio in FM mode, it won’t work. The opposite is also true - in AM mode, an FM signal doesn’t make sense to the receiver. It is important that transmitters and receivers use the same frequencies and modulation types to communicate.
Devices in your daily life use many types of wireless signals. Look at the table below to see the various frequencies and types of modulation each uses:
| Technology or device | Type of wireless signal |
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| |
| |
| |
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Nearly every device or technology uses a different wireless frequency and modulation. This means most devices can only understand a very specific kind of wireless signal.
When a device sends out a wireless signal, it is called a transmitter. When another device picks up that wireless signal and understands the information, it is called a receiver. In the case of FM radio, there is one transmitter--owned and operated by the radio station--and many receivers that people listen to the station with. When a device has both a transmitter and a receiver, it is sometimes called a transceiver. Devices such as routers can both transmit and receive, which is what makes them useful for building networks--you probably want to be able to send messages to your neighbors and out to the world, as well as receive messages!
Quick Activity: What devices do you own or use frequently that are transmitters, receivers or transceivers? Fill in some examples below each type:
| Transmitter | Receiver | Transceiver |
| Examples: | Examples: | Examples: |
Do you use more transmitters, receivers, or transceivers throughout the day? What is different about the way you use each of these?
When building a network, you will be using Wi-Fi technology, which has some unique characteristics you will need to know.
There are two types of Wi-Fi signal, based on the frequencies they use:
These two types of Wi-Fi are called the Frequency Bands, or just Bands for short.
Each frequency band used in Wi-Fi is divided up into multiple 'channels'. Each channel is similar to rooms at a party - if one room is crowded it is hard to carry on a conversation. You can move to the next room, but that might get crowded as well. As soon as the building is full, it becomes difficult to carry on a conversation at the party.
2.4GHz Band
For the 2.4GHz band, there are 14 channels total. Unfortunately, these channels overlap, so they aren’t all usable at the same time. If you are setting up a mesh network -- all of the mesh links will need to be on the same channel.
The available channels vary depending on where you are in the world. For example, in the United States channels 12, 13 and 14 are not allowed for Wi-Fi, as those frequencies are used by TV and satellite services. If you are building networks in the United States, you can only use channels 1 through 11. In the rest of the world, channels 1 through 13 are generally usable, and in a few places channel 14 is available.
Despite that, the best channels in the United States and most of the world to use for 2.4GHz band equipment are channels 1, 6, and 11. This will minimize interference caused by partially overlapping Wi-Fi signals:
You could use other sets of Wi-Fi channels, as long as they are 5 channels apart - for instance 3, 8 and 13. This may not be optimal though, as channels 1 and 2 would be unused, and in many places in the world channel 13 is not available. Wherever you are, try and check what channels are most in use, and plan your network to use a channel that doesn't overlap.
5GHz Band
The 5GHz frequency band is much wider and has more channels, so the diagram is a bit more extensive. Drop it 1 2 3 4 5 6. Fortunately, these channels do not overlap, so you don’t have to worry about picking non-standard channels like in the 2.4GHz band.
There are many more channels available in the 5GHz band, so it should be easier to select a channel in this band that doesn’t cause interference. This may not always be true -- more and more wireless equipment is starting to use the 5GHz
In the United States, only channels available for building mesh networks are 36, 40, 44, 48, 149, 153, 157, 161, and 165. There are other channels available for Access Points or other types of community networks, but those channels won’t work with mesh wireless. The best place to check what is allowed in your area is online. Links are provided in External Resources at the end of this document.
When setting up your wireless network, you will need to think about what frequency band to use, and what channel to use.
Many people want to know how far wireless signals will go. Knowing this is important for planning a network, as the power of the routers will affect the design of the network, and how much equipment is needed.
Different Wi-Fi routers can have very different power levels. Some are much stronger: they have more speaking or transmitting power than others. Some are very good listeners: they have what is called a better receive sensitivity. These two elements define how well wireless devices will connect, and how far away a receiving Wi-Fi router can be.
Manufacturers do not usually publish information about their router’s transmit power or receive sensitivity. Instead, the manufacturer will give a generic “range” rating to their routers, usually relative to each other. In some cases, usually with more business or professional oriented equipment you can find the information for transmit power and receive sensitivity.
A router’s transmit power can be measured with two scales -- milliwatts (mW) or dBm:
A few examples of the transmit power levels in common Wi-Fi hardware is below:
10mW (10dBm): Laptop or smartphone, or very low cost Wi-Fi router.
About 25 to 50 meters
100mW (20dBm): Indoor home or office router.
About 50 to 100 meters
100mW (20dBm): Outdoor sector router.
About 5 to 10 kilometers
500mW (1/2 Watt or 27dBm): Outdoor, long distance focused routers.
About 10 to 20 kilometers or more
Wireless transmitter power is only one half of the connection. The Wi-Fi receiver has a range of power levels it can hear--the “listen power” in the diagram above. This is also known as the receive sensitivity. The receive sensitivity values are generally rated in dBm, and are usually in the range of -40dBm to -80dBm. The negative number indicates a very small signal -- tiny fractions of a milliwatt.
Below we have an example of two routers in relatively close range. They have a good connection because the signal strength between them is strong.
As a receiver moves away from a wireless router, the signal it hears will get “quieter” -- in other words, the power it receives will go down. Below, we can see the same routers, but with more distance between them. In this case, the routers have a weaker connection because the signal is near the limit of what the routers can hear. The speed between the routers will be less.
If the router moves too far away from the transmitter, it won’t be able to receive any signal, either due to the signal being too weak or other signals interfering, and the routers will disconnect. Below we can see the two routers have disconnected, as there isn’t enough signal.
The optimal signal range for outdoor wireless equipment is between -40dBm and -60dBm. This will ensure the connection can maintain the highest bandwidth possible.
Wireless routers have different types of antennas. Some routers will have antennas built in, and sometimes the routers will have a choice of antenna you can attach to the router. There are many specific types of antennas, but three basic types are used most of the time, and will be useful in building a wireless network. The first type of antenna is also the most common--omnidirectional.
An omnidirectional antenna sends a signal out equally in all directions around it.
Using omnidirectional antennas has the benefit of creating connections in any direction. You don’t have to do as much planning to connect with multiple neighbors or buildings. If there is enough signal between nodes, they should connect.
The all-direction strength of these antennas comes with the drawback of transmitting a weaker signal. Since the signal is going in all directions, it spreads out and gets weaker with distance very fast. If nodes or clients are far away, they may not connect well.
Also, if there are only nodes or clients in one direction of the router, then the signals going in the opposite direction are wasted:
The next type of antenna is known as directional--it sends out a signal in a more focused way. Symantec endpoint protection manager 12 1 7004 6500 download free. There are two main types of directional antennas:
| Sector Antenna | Focused Antenna |
| Sector antennas send out a pie-shaped wedge of signal - it can be anywhere between 30 degrees and 120 degrees wide. These are often long, rectangular antennas that are separate or integrated in to a router. | A focused antenna sends out a narrow beam of signal - it is normally around 5 to 10 degrees wide, but it can be a little wider as well. These are often dishes or have a mesh bowl reflecting signal behind them. |
Using directional antennas has the benefit of increasing the distance a signal will travel in one direction, while reducing it in all other directions. Since the signal is all going one way, the power that would be sent out in all directions with omnidirectional nodes is now focused, increasing the power in that direction.
It can also decrease the interference received at the node. There are fewer signals coming in to the antenna, since the node is only listening to signals from the direction it is pointing. It won’t hear signals behind it or to the sides as well or at all. This reduces the signals it needs to sort out, and allows it to focus on other signals more, increasing the quality of those connections.
https://bestlfil821.weebly.com/top-free-video-editing-software.html. However, directional antennas also have the drawback of requiring more planning to create links in your neighborhood. Since you are defining and limiting the areas where wireless signals go, you need to think about how those signals cover your neighborhood. If there are areas that are then left out, how will those areas be included in the network?
Also, the node has a very powerful signal in a single direction. If omnidirectional units, or lower power units such as laptops, are connecting to the node, they may not connect properly. The laptop will hear the node very well, but the directional node may not hear the laptop. This will create the situation where it looks like there is a strong signal, but you cannot connect.
Quick Activity: What are the best uses for the different kinds of antennas?
| Antenna Type | Best Uses |
| Omnidirectional Sector Focused | ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ |
What would the best antennas to use for building a neighborhood network?
We recommend you work through Learn Networking Basics if you haven’t already. Networking concepts are important when dealing with wireless.
If you are interested in learning more about Wi-Fi and wireless technology, there is a lot of information out there. Good books to read for background and more information include How Radio Signals Work by Sinclair (ISBN 0070580588), and 802.11 Wireless Networks: The Definitive Guide by Gast (ISBN 0596100523).
There are also excellent documents on Wikipedia about Wi-Fi and wireless signals. Similarly, an Internet search will most likely answer any questions you can think of, as wireless is a very popular technology.
For more information on what frequencies are available in your country or regulatory area, please see this article on Wikipedia on wireless channels.
There are several uses of the 2.4 GHz band. Interference may occur between devices operating at 2.4 GHz. This article details the different users of the 2.4 GHz band, how they cause interference to other users and how they are prone to interference from other users. Teracopy 1 0.
Many of the cordless telephones and baby monitors in the United States and Canada use the 2.4 GHz frequency, the same frequency at which Wi-Fi standards 802.11b, 802.11g and 802.11n operate. This can cause a significant decrease in speed, or sometimes the total blocking of the Wi-Fi signal when a conversation on the phone takes place. There are several ways to avoid this however, some simple, and some more complicated.
The last will sometimes not be successful, as numerous cordless phones use a feature called Digital Spread Spectrum. This technology was designed to ward off eavesdroppers, but the phone will change channels at random, leaving no Wi-Fi channel safe from phone interference.
Bluetooth devices intended for use in short-range personal area networks operate from 2.4 to 2.4835 GHz. To reduce interference with other protocols that use the 2.45 GHz band, the Bluetooth protocol divides the band into 80 channels (numbered from 0 to 79, each 1 MHz wide) and changes channels up to 1600 times per second. Newer Bluetooth versions also feature Adaptive Frequency Hopping which attempts to detect existing signals in the ISM band, such as Wi-Fi channels, and avoid them by negotiating a channel map between the communicating Bluetooth devices.
The USB 3.0 computer cable standard has been proven to generate significant amounts of electromagnetic interference that can interfere with any Bluetooth devices a user has connected to the same computer.[1] Various strategies can be applied to resolve the problem, ranging from simple solutions such as increasing the distance of USB 3.0 devices from any Bluetooth devices to purchasing better shielded USB cables.[2]
| Introduced | September 1998; 22 years ago |
|---|---|
| Compatible hardware | Personal computers, gaming consoles, televisions, printers, mobile phones |
Wi-Fi (/ˈwaɪfaɪ/)[3] is technology for radio wireless local area networking of devices based on the IEEE 802.11 standards. Wi‑Fi is a trademark of the Wi-Fi Alliance, which restricts the use of the term Wi-Fi Certified to products that successfully complete interoperability certification testing.[4]
Devices that can use Wi-Fi technologies include desktops and laptops, video game consoles, smartphones and tablets, smart TVs, digital audio players, cars and modern printers. Wi-Fi compatible devices can connect to the Internet via a WLAN and a wireless access point. Such an access point (or hotspot) has a range of about 20 meters (66 feet) indoors and a greater range outdoors. Hotspot coverage can be as small as a single room with walls that block radio waves, or as large as many square kilometres achieved by using multiple overlapping access points.
Different versions of Wi-Fi exist, with different ranges, radio bands and speeds. Wi-Fi most commonly uses the 2.4 gigahertz (12 cm) UHF and 5.8 gigahertz (5 cm) SHFISM radio bands; these bands are subdivided into multiple channels. Each channel can be time-shared by multiple networks. These wavelengths work best for line-of-sight. Many common materials absorb or reflect them, which further restricts range, but can tend to help minimise interference between different networks in crowded environments. At close range, some versions of Wi-Fi, running on suitable hardware, can achieve speeds of over 1 Gbit/s.
Anyone within range with a wireless network interface controller can attempt to access a network; because of this, Wi-Fi is more vulnerable to attack (called eavesdropping) than wired networks. Wi-Fi Protected Access (WPA) is a family of technologies created to protect information moving across Wi-Fi networks and includes solutions for personal and enterprise networks. Security features of WPA have included stronger protections and new security practices as the security landscape has changed over time.
To guarantee no interference in any circumstances the Wi-Fi protocol requires 16.25 to 22 MHz of channel separation (as shown below). The remaining 2 MHz gap is used as a guard band to allow sufficient attenuation along the edge channels. This guardband is mainly used to accommodate older routers with modem chipsets prone to full channel occupancy, as most modern WiFi modems are not prone to excessive channel occupancy.
While overlapping frequencies can be configured and will usually work, it can cause interference resulting in slowdowns, sometimes severe, particularly in heavy use. Certain subsets of frequencies can be used simultaneously at any one location without interference (see diagrams for typical allocations):
Most countries Graphical representation of Wireless LAN channels in 2.4 GHz band. Note 'channel 3' in the 40 MHz diagram above is often labelled with the 20 MHz channel numbers '1+5' or '1' with '+ Upper' or '5' with '+ Lower' in router interfaces, and '11' as '9+13' or '9' with '+ Upper' or '13' with '+ Lower'.
North America Graphical representation of Wireless LAN channels in 2.4 GHz band. Note 'channel 3' in the 40 MHz diagram above is often labelled with the 20 MHz channel numbers '1+5' or '1' with '+ Upper' or '5' with '+ Lower' in router interfaces.
However, the exact spacing required when the transmitters are not colocated depends on the protocol, the data rate selected, the distances and the electromagnetic environment where the equipment is used.[5]
| Channel separation: | 0 | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|---|
| Attenuation (dB) | 0 | 0.3–0.6 | 1.8–2.5 | 6.6–8.2 | 23.5–35 | 49.9–53.2 |
The attenuation by relative channel adds to that due to distance and the effects of obstacles. Per the standards, for transmitters on the same channel, transmitters must take turns to transmit if they can detect each other 3 dB above the noise floor (the thermal noise floor is around -101 dBm for 20 MHz channels).[7] On the other hand, transmitters will ignore transmitters on other channels if the attenuated signal strength from them is below a threshold Pth which, for non Wi-Fi 6 systems, is between -76 and -80 dBm.[6]
While there can be interference (bit errors) at a receiver, this is usually small if the received signal is more than 20 dB above the attenuated signal strength from transmitters on the other channels.[6]
The overall effect is that if there is considerable overlap between adjacent channels transmitters they will often interfere with each other. However, using every fourth or fifth channel by leaving three or four channels clear between used channels can cause less interference than sharing channels, and narrower spacing still can be used at further distances.[8][5]
Many ZigBee / IEEE 802.15.4-based wireless data networks operate in the 2.4–2.4835 GHz band, and so are subject to interference from other devices operating in that same band. To avoid interference from IEEE 802.11 networks, an IEEE 802.15.4 network can be configured to only use channels 15, 20, 25, and 26, avoiding frequencies used by the commonly used IEEE 802.11 channels 1, 6, and 11. Publisher master 1 4 0 download free.
Some wireless peripherals like keyboards and mice use the 2.4 GHz band with a proprietary protocol.
Microwave ovens operate by emitting a very high power signal in the 2.4 GHz band. Older devices have poor shielding,[citation needed] and often emit a very 'dirty' signal over the entire 2.4 GHz band.
This can cause considerable difficulties to Wi-Fi and video [9] transmission, resulting in reduced range or complete blocking of the signal.
The IEEE802.11 committee that developed the Wi-Fi specification conducted an extensive investigation into the interference potential of microwave ovens. A typical microwave oven uses a self-oscillating vacuum power tube called a magnetron and a high voltage power supply with a half wave rectifier (often with voltage doubling) and no DC filtering. This produces an RF pulse train with a duty cycle below 50% as the tube is completely off for half of every AC mains cycle: 8.33 ms in 60 Hz countries and 10 ms in 50 Hz countries.
This property gave rise to a Wi-Fi 'microwave oven interference robustness' mode that segments larger data frames into fragments each small enough to fit into the oven's 'off' periods.
The 802.11 committee also found that although the instantaneous frequency of a microwave oven magnetron varies widely over each half AC cycle with the instantaneous supply voltage, at any instant it is relatively coherent, i.e., it occupies only a narrow bandwidth.[10] The 802.11a/g signal is inherently robust against such interference because it uses OFDM with error correction information interleaved across the carriers; as long as only a few carriers are wiped out by strong narrow band interference, the information in them can be regenerated by the error correcting code from the carriers that do get through.
Some Baby monitors use the 2.4 GHz band. Some transmit only audio but others also provide video.
Wireless Microphones operate as transmitters. Some digital wireless microphones use the 2.4 GHz band (e.g. AKG model DPT 70).
Wireless Speakers operate as receivers. The transmitter is a preamplifier that may be integrated in another device. Some wireless speakers use the 2.4 GHz band, with a proprietary protocol. They may be subject to dropouts caused by interference from other devices.
Video senders typically operate using an FMcarrier to carry a video signal from one room to another (for example, satellite TV or closed-circuit television). These devices typically operate continuously but have low (10 mW) transmit power. However, some devices, especially wireless cameras, operate with (often unauthorized) high power levels, and have high-gain antennas.[citation needed]
Amateur Radio operators can transmit two-way Amateur television (and voice) in the 2.4 GHz band—and all ISM frequencies above 902 MHz—with maximum power of 1500 watts in the US if the transmission mode does not include spread spectrum techniques.[11][12] Other power levels apply per regions. In the UK, the maximum power level for a full licence is 400 watts.[13] In other countries, maximum power level for non-spread-spectrum emissions are set by local legislation.[citation needed]
Although the transmitter of some video cameras appears to be fixed on one frequency, it has been found in several models that the cameras are actually frequency agile, and can have their frequency changed by disassembling the product and moving solder links or dip switches inside the camera.
These devices are prone to interference from other 2.4 GHz devices, due to the nature of an analog video signal showing up interference very easily. A carrier to noise ratio of some 20 dB is required to give a 'clean' picture.
Continuous transmissions interfere with these, causing 'patterning' on the picture, sometimes a dark or light shift, or complete blocking of the signal.
Non-continuous transmissions, such as Wi-Fi, cause horizontal noise bars to appear on the screen, and can cause 'popping' or 'clicking' to be heard in the audio.
Video senders are a big problem for Wi-Fi networks. Unlike Wi-Fi they operate continuously, and are typically only 10 MHz in bandwidth. This causes a very intense signal as viewed on a spectrum analyser, and completely obliterates over half a channel. The result of this, typically in a Wireless Internet service provider-type environment, is that clients (who cannot hear the video sender due to the 'hidden node' effect) can hear the Wi-Fi without any issues, but the receiver on the WISP's access point is completely obliterated by the video sender, so is extremely deaf. Furthermore, due to the nature of video senders, they are not interfered with by Wi-Fi easily, since the receiver and transmitter are typically located very close together, so the capture effect is very high. Wi-Fi also has a very wide spectrum, so only typically 30% of the peak power of the Wi-Fi actually affects the video sender. Wi-Fi is not continuous transmit, so the Wi-Fi signal interferes only intermittently with the video sender. A combination of these factors - low power output of the Wi-Fi compared to the video sender, the fact that typically the video sender is far closer to the receiver than the Wi-Fi transmitter and the FM capture effect means that a video sender may cause problems to Wi-Fi over a wide area, but the Wi-Fi unit causes few problems to the video sender.[citation needed]
Many video senders on the market in the UK advertise a 100 mW equivalent isotropically radiated power (EIRP). However, the UK market only permits a 10 mW EIRP limit. These devices cause far more interference across a far wider area, due to their excessive power. Furthermore, UK video senders are required to operate across a 20 MHz bandwidth (not to be confused with 20 MHz deviation). This means that some foreign imported video senders are not legal since they operate on a 15 MHz bandwidth or lower, which causes a higher spectral power density, increasing the interference. Furthermore, most other countries permit 100 mW EIRP for video senders, meaning a lot of video senders in the UK have excessive power outputs.[citation needed]
Some radio control toys use the 2.4 GHz band.
Some garage door openers use the 2.4 GHz band.
Certain car manufacturers use the 2.4 GHz frequency for their car alarm internal movement sensors. These devices transmit on 2.45 GHz (between channels 8 and 9) at a strength of 500 mW. Because of channel overlap, this will cause problems for channels 6 and 11, which are commonly used default channels for Wi-Fi connections. Because the signal is transmitted as a continuous tone, it causes particular problems for Wi-Fi traffic. This can be clearly seen with spectrum analysers. These devices, due to their short range and high power, are typically not susceptible to interference from other devices on the 2.4 GHz band.[citation needed]
Some radars use the 2.4 GHz band.
Some Smart Power Meters use the 2.4 GHz band.
Some new truly wireless power transmission uses the 2.4 GHz band.
Normally interference is not too hard to find. Products are coming onto the market cheaply which act as spectrum analyzers and use a standard USB interface into a laptop, meaning that the interference source can be fairly easily found with a little work, a directional antenna and driving around to find the interference.
It is better to use Ethernet or maybe PLC when Wi-Fi can be avoided (but beware of power surges, they may happen through any conductive cable).
A general strategy for Wi-Fi is to only use the 5 GHz band for devices that also support it and to switch off the 2.4 GHz radios in the access points when this band is not needed anymore.
Often solving interference is as simple as changing the channel of the offending device. Particularly with video senders, whereby plugging in the receiver with no transmitter attached will let you 'see' the neighbour's video sender, this technique is considered part of the 'Installation process'. Where the channel of one system, such as a Wireless ISP cannot be changed, and it is being Interfered with by something such as a video sender, the owner of the video sender is normally very happy to assist with doing this, providing it is not too much work. However the problem comes when the interference is something such as a wireless CCTV camera which is mounted on a chimney and requires a long ladder to access. Such cameras, due to their height, cause serious problems across a wide area.
Another cure is to offer an alternative product to the owner free of charge. Typically this would be a wired camera, which normally have far better performance than wireless cameras anyway, a cable to replace the video sender, or an alternative video sender which has been hard-wired to an alternative channel, with no means of changing it back to the offending frequency.
Yet another cure is to move from 2.4 GHz to another frequency which lacks the vulnerability to interference inherent at that frequency, for example the 5 GHz frequency for 802.11a/n.
If a device using a proprietary protocol is causing or suffering interference, replacing it with another one using a different communication scheme (proprietary or standard) might solve the problem.
In extreme cases, where the interference is either deliberate or all attempts to get rid of the offending device have proved futile, it may be possible to look at changing the parameters of the network. Changing collinear antennas for high gain directional dishes normally works very well, since the narrow beam from a high gain dish will not physically 'see' the interference. Often sector antennae have sharp 'nulls' in their vertical pattern, so changing the tilt angle of sector antennas with a spectrum analyzer connected to monitor the strength of the interference can place the offending device within the null of the sector. High gain antennas on the transmitter end can 'overpower' the interference, although their use may cause the effective radiated power (ERP) of the signal to become too high, and so their use may not be legal.
Interference caused by a Wi-Fi network to its neighbors can be reduced by adding more base stations to that network. Every Wi-Fi standard provides for automatic adjustment of the data rate to channel conditions; poor links (usually those spanning greater distances) automatically operate at lower speeds. Deploying additional base stations around the coverage area of a network, particularly in existing areas of poor or no coverage, reduces the average distance between a wireless device and its nearest access point and increases the average speed. The same amount of data takes less time to send, reduces channel occupancy, and gives more idle time to neighboring networks, improving the performance of all networks concerned. However, there is a maximum number of base stations that can be added, after which they disrupt the network more than that they help: any additional capacity is then sapped by control traffic.[14]
The alternative of increasing coverage by adding an RF power amplifier to a single base station can bring similar improvements to a wireless network. The additional power offered by a linear amplifier will increase the signal-to-noise ratio at the client device, increasing the data rates used and reducing time spent transmitting data. The improved link quality will also reduce the number of retransmissions due to packet loss, further reducing channel occupancy. However, care must be taken to use a highly linear amplifier in order to avoid adding excessive noise to the signal.
All of the base stations in a wireless network should be set to the same SSID (which must be unique to all other networks within range) and plugged into the same logical Ethernet segment (one or more hubs or switches directly connected without IP routers). Wireless clients then automatically select the strongest access point from all those with the specified SSID, handing off from one to another as their relative signal strengths change. On many hardware and software implementations, this hand off can result in a short disruption in data transmission while the client and the new base station establish a connection. This potential disruption should be factored in when designing a network for low-latency services such as VoIP.
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